Some of the other changes include bringing in a supervisor to the scene when a weapon is involved, all patrol cars are now equipped with helmets and long batons, and the supply of bean bags has doubled.

"Every decision that we train that officer to make is around preserving the sanctity of life," explained Suzy Loftus, President of the San Francisco Police Commission.

The mayor and police chief still support the use of tasers, but said little about the topic which has become very controversial and political.

"It is one tool here. It can be valuable in certain circumstances," said Lee.